Designing a device for production by silicon micromachining is very different from macro-scale mechanical design. In the macro-scale, a designer can create a three-dimensional model of the device that is sufficient for a design program to translate into tool paths for device production. In contrast, for a silicon micromachined device, the designer must create a set of process-specific masks that are used to fabricate the device. Creating the masks is equivalent to requiring the macro-scale designer to design not only the product, but also the tools used to construct the product. Masks are dependent on the process used for fabrication and can have complex interactions within a production system, therefore creation of the masks is a significant challenge to innovative device design and the manufacture of a device on multiple processes.
What is desired is a technique for translating a designer's three-dimensional model of a product directly into the masks used to produce the model.
Previous attempts to create MEMS mask sets have used existing technology in process simulators, for example programs that can simulate fabrication from masks that are supplied with process data for a specific production process. Typically, a trial mask set is used to produce a three-dimensional object that is then compared to the desired object. Differences between the two objects are used to alter the trial mask set. The process is repeated until a mask set is found which correctly produces the desired part. The process is computationally intensive and has been unable yet to produce production masks for complex, multiple-layer surface micromachined devices.